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CentOS 7.0 - man page for io_cancel (centos section 2)

IO_CANCEL(2)				      Linux Programmer's Manual 				 IO_CANCEL(2)

NAME
io_cancel - cancel an outstanding asynchronous I/O operation
SYNOPSIS
#include <linux/aio_abi.h> /* Defines needed types */ int io_cancel(aio_context_t ctx_id, struct iocb *iocb, struct io_event *result); Note: There is no glibc wrapper for this system call; see NOTES.
DESCRIPTION
The io_cancel() system call attempts to cancel an asynchronous I/O operation previously submitted with io_sub- mit(2). The iocb argument describes the operation to be canceled and the ctx_id argument is the AIO context to which the operation was submitted. If the operation is successfully canceled, the event will be copied into the memory pointed to by result without being placed into the completion queue.
RETURN VALUE
On success, io_cancel() returns 0. For the failure return, see NOTES.
ERRORS
EAGAIN The iocb specified was not canceled. EFAULT One of the data structures points to invalid data. EINVAL The AIO context specified by ctx_id is invalid. ENOSYS io_cancel() is not implemented on this architecture.
VERSIONS
The asynchronous I/O system calls first appeared in Linux 2.5.
CONFORMING TO
io_cancel() is Linux-specific and should not be used in programs that are intended to be portable.
NOTES
Glibc does not provide a wrapper function for this system call. You could invoke it using syscall(2). But instead, you probably want to use the io_cancel() wrapper function provided by libaio. Note that the libaio wrapper function uses a different type (io_context_t) for the ctx_id argument. Note also that the libaio wrapper does not follow the usual C library conventions for indicating errors: on error it returns a negated error number (the negative of one of the values listed in ERRORS). If the system call is invoked via syscall(2), then the return value follows the usual conventions for indicating an error: -1, with errno set to a (positive) value that indicates the error.
SEE ALSO
io_destroy(2), io_getevents(2), io_setup(2), io_submit(2), aio(7)
COLOPHON
This page is part of release 3.53 of the Linux man-pages project. A description of the project, and informa- tion about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/. Linux 2013-04-10 IO_CANCEL(2)
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